(1) Field of the Invention
This invention relates to an optical waveguide structure suitable for coupling an optical device, such as a laser diode or a photodiode, included in an optical module used for optical communication or optical information processing and a transmission medium, such as an optical fiber or an optical waveguide and an optical module using such an optical waveguide structure.
(2) Description of the Related Art
For example, it is possible to make the integration level of surface emitting laser diodes which form an array higher than that of ordinary edge emitting laser diodes which form an array. That is to say, compared with ordinary edge emitting laser diodes, a large number of surface emitting laser diodes can be mounted on a board. Therefore, surface emitting laser diodes are considered to be key components used for optical communication in which large capacity transmission is needed or optical information processing in which a high integration level is needed.
To fabricate a module in which surface emitting laser diodes are mounted on a board and in which laser beams are inputted into transmission media, such as optical fibers, the optical fibers will be located perpendicularly to the board, especially if a special optical system, such as a mirror, for deflecting light is not used.
FIG. 48 is a sectional view of a feature of a module in which an optical fiber is located perpendicularly to a board. In FIG. 48, a board 1, a surface type optical device 2, an optical fiber 3, and a core 3A of the optical fiber 3 are shown. The surface type optical device 2 is a surface emitting laser diode, a photodiode, or the like.
If the optical fiber 3 is located perpendicularly to the board 1 as shown in FIG. 48, there are problems with mounting. For example, the work is troublesome. Moreover, this structure is not suitable for realizing a flat optical module. Therefore, it is preferable to locate the optical fiber 3 parallel to the board 1.
Optical modules have various structures. In some cases, it is necessary to input light outputted from a surface emitting laser diode into an optical waveguide. Such an optical module should have a structure in which a surface emitting laser diode and an optical waveguide are mounted on the same board from the manufacturing viewpoint.
This needs an optical system for deflecting light from a surface type optical device almost squarely to couple the surface type optical device mounted on a board and an optical fiber or an optical waveguide. A system in which reflection by an inclined mirror located at an appropriate position on an optical path is used is known as such an optical system (see, for example, Japanese unexamined Patent Publication No. 62-35304, Japanese unexamined Patent Publication No. 5-88029, and International Publication No. 00/08505.)
FIG. 49 is a sectional view of a feature of an optical system in which an inclined mirror is located at an appropriate position on an optical path. In FIG. 49, a lens 4 and an inclined mirror 5 are shown. The same symbols that are used in FIG. 48 indicate the same components or have the same meanings.
As shown in FIG. 49, an optical fiber 3 is located parallel to a board 1. Light outputted from a surface type optical device 2 mounted on the board 1 is inputted into the inclined mirror 5 via the lens 4, is squarely reflected there, and is inputted into the optical fiber 3.